Which GPS?

Garmin has better maps than magellan or tom tom. The tom tom I believe comes with lifetime updates and is extremely user friendly. The magellan is not as user friendly. I own a Garmin and the only problem I have is that I have to use my fingernail on the touchscreen because I have larger fingers and the resistive touchscreen will get confused by too much of the screen being touched.

Another option would be to get her an iphone or android and teach her how to use it because they have a pretty decent gps system.